1. Field of the Invention
The present invention relates to a test device for a liquid crystal display (LCD) panel, and more particularly, to a backlight unit having increased lifetime for an LCD panel test device.
2. Discussion of the Related Art
One type of test device of the related art for a liquid crystal display (LCD) panel allows a naked eye evaluation of whether the LCD panel is bad or good.
FIGS. 1 and 2 illustrate a related art test device for an LCD panel.
As shown in FIGS. 1 and 2, the related art test device for an LCD panel includes a tester 2 and a loading/unloading unit 7. The tester 2 is arranged at one side of a main body 1 to test an LCD panel 10. The loading/unloading unit 7 is arranged at one side of the tester 2, and receives and stores an LCD panel 10 to be tested.
The related art test device of the LCD panel further includes a carrier 9 arranged to be movable in left and right directions to carry the LCD panel 10 from the loading/unloading unit 7 to the tester 2 and vice versa.
The tester 2 includes a probe unit 3 and a work table 4. The work table 4 contacts the LCD panel 10 with the probe unit 3 and supplies a light source. The work table 4 includes a polarizing plate 4a and a backlight 4b. A moving stage 5 is arranged at the rear of the work table 4, and serves to align the work table 4 with respect to the probe unit 3 and to move the work table 4 into contact with the probe unit 3.
The loading/unloading unit 7 is provided with a sub table 8 that tilts the LCD panel 10 carried from a loader (not shown) at a predetermined angle (for example, 60°).
In addition, a microscope 6 is arranged at the front of the tester 2. The microscope may be moved in all directions. The microscope 6 serves to allow a worker to perform a more detailed inspection of the LCD panel 10 when a defect is found in the LCD panel using the naked eye.
A test process using the related art test device for an LCD panel will now be described in brief.
First, the LCD panel 10 is transferred from the loader of the loading/unloading unit 7 to the sub table 8. The sub table 8 is tilted at a predetermined angle and the LCD panel 10 is transferred to the carrier 9. The carrier 9 carries the LCD panel 10 to the tester 2. When the LCD panel 10 to be tested is positioned in the tester 2, the moving stage drives the work table 4 forward and the LCD panel 10 is fixed to the carrier 9 using a vacuum. A pad (not shown) of the fixed LCD panel 10 is electrically connected to a lead pin (not shown) of the probe unit 3.
Once the LCD panel 10 is electrically connected with the probe unit 3, a predetermined image signal is applied through the probe unit 3 while a lamp of the backlight 4b is varied using various patterns provided by a pattern generator. The pattern generator is an external image signal input device. The worker can identify a defect of the panel by viewing the displayed pattern from the LCD panel 10 with the naked eye.
However, the related art test device of the LCD panel has the following problems.
First, in the related art test device of the LCD panel, a cold fluorescent lamp (CFL) or a cold cathode fluorescent lamp (CCFL) is used as the backlight 4b. However, these types of backlight 4b have a problem in that frequent blinking on and off these lamp types rapidly decreases the lifetime of the lamp. The shortened lifetime results in the backlight 4b having to be frequently replaced increasing the cost of operating the tester.
In addition, the lifetime of the backlight 4b is decreased due to heating of the backlight 4b by heat generated during operation of the backlight 4b. 
As the light source nears the end of its life, the light source may fail to illuminate particular portions of the LCD panel (for example, corner portions) during a test of the LCD panel. As a result, a defect in the particular portion of the LCD panel may not be effectively detected.